I'm finding I don't actually need custom Lua in many cases to achieve fairly good results though - WA is actually very robust without the need for custom Lua, it's just not always the most accessible in 'telling. I make fairly extensive use of WeakAuras - initially using it's provided 'template' options to program auras, and gradually into adding my own custom Lua to do anything from forcing an Aura to always be active independent of triggers, to playing custom sound effects and animations. Wago of the Minute Necrolord Demon Hunter - Fodder To The Flame Demon Out.
When properly paired together: Core, Utilities & Dynamic contain an exhaustive setup for Beast Mastery Hunter, Marksmanship Hunter and Survival Hunter by covering rotational abilities, cooldowns, resources and utilities. Complete Hunter WeakAuras for World of Warcraft: Shadowlands. Database of sharable World of Warcraft addon elements.